De-client tracing.TraceController interface

sky/tools/debugger/trace_collector.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sky/tools/debugger/trace_collector.h"
 
 namespace sky {
 namespace debugger {
 
 TraceCollector::TraceCollector(mojo::ScopedDataPipeConsumerHandle source)
     : drainer_(this, source.Pass()), is_complete_(false) {
 }
 
 TraceCollector::~TraceCollector() {
 }
 
 void TraceCollector::GetTrace(TraceCallback callback) {
-  DCHECK(!callback_.is_null());
+  DCHECK(callback_.is_null());
+  DCHECK(!callback.is_null());
   if (is_complete_) {
     callback.Run(GetTraceAsString());
     return;
   }
   callback_ = callback;
 }
 
 void TraceCollector::OnDataAvailable(const void* data, size_t num_bytes) {
   DCHECK(!is_complete_);
   const char* chars = static_cast<const char*>(data);
   trace_.insert(trace_.end(), chars, chars + num_bytes);
 }
 
 void TraceCollector::OnDataComplete() {
   DCHECK(!is_complete_);
   is_complete_ = true;
   if (!callback_.is_null())
     callback_.Run(GetTraceAsString());
 }
 
 std::string TraceCollector::GetTraceAsString() {
   return std::string(&trace_.front(), trace_.size());
 }
 
 }  // namespace debugger
 }  // namespace sky